1. Field of the Invention
The present invention relates generally to a plasma treatment method using electron cyclotron resonance, and a system using the same.
2. Related Background Art
Recently, as a technique for carrying out a thin film deposition or etching with plasmas, the electron cyclotron resonance (ECR) plasma treatment method for causing a microwave discharge using a resonance phenomenon between the cyclotron motion of electrons and microwaves in a magnetic field has been widely noticed. According to this method, since high vacuum and high density plasmas can be produced by the electrodeless discharge, there are advantages in that it is possible to carry out a high-speed surface treatment and it is not likely that wafers will be contaminated.
Referring to FIG. 16, an example of a conventional plasma treatment system for carrying out the ECR plasma treatment will be described by an example of a thin film deposition treatment. A microwave of, e.g., 2.45 GHz, is supplied to a plasma producing chamber 1A via a waveguide (not shown). Simultaneously, a magnetic field of a predetermined intensity, e.g., 875 gausses, is applied to the plasma producing chamber 1A by means of an electromagnetic coil 10 to produce high density plasmas of plasma producing gases, e.g., Ar gas and O.sub.2 gas, by the interaction (resonance) between the microwave and the magnetic field. These plasmas activate a reactive gas, e.g., SiH.sub.4 gas, which is introduced into a thin film deposition chamber 1B, to form an active species (for example, such as free radicals or ions), so that the sputter etching and the deposition simultaneously proceed on the surface of a silicon wafer W on a transfer table 11. The sputter etching operation and the deposition operation, which are contrary to each other, are controlled so that the deposition operation is macroscopically predominant over the sputter etching operation. Thus, the deposition is carried out as a whole.
By the way, with the scale down and high integration of the pattern of a semiconductor device, the thickness of a film, e.g., an interlayer insulator film, has been very thin. In addition, a demand for still finer patterning has been made, so that it has been demanded that a plasma treatment, such as the plasma deposition and the plasma etching, should achieve still higher inplane uniformity. Therefore, it is required to establish process conditions corresponding to such demands. However, since the behavior of the process has many unclear points, particularly since the history of the wafer treatment using the ECR is short, it is very difficult to design the system and to set the process conditions.
For example, the diameter of a chamber, the electron densities at various distances from a wafer, and the magnetic field gradient have been determined by trial and error. This operation needs a long time and much labor, and it is difficult for even an expert to carry out the operation. Therefore, it is not easy to carry out a plasma treatment achieving a high inplane uniformity, and a demand for establishing a technique for carrying out such a plasma treatment is made.